Carbon dioxide absorber for anesthetic administering apparatus



W. W. HAY

June 3, 1958 CARBON DIOXIDE ABSORBER FOR ANESTHETIC ADMINISTERING APPARATUS 3 Sheets-Sheet 1 Filed April 13, 1955 FIG.

ATTORNEY June 3, 1958 w. w. HAY 2,837,413

4 CARBON DIOXIDE ABSORBER FOR ANESTHETIC ADMINISTERING APPARATUS Filed April 13, 1955 3 Sheets-Sheet 3 F l G. 7

H K 55 i INVENTOR WAYN E W. HAY

ATTORNEY CARBON DIOXIDE ABSQRBER FGR ANESTHETIC ADMENISTERKNG APPARATUS Wayne W. Hay, Madison, Wis, assignor to Air Reduction Company, Incorporated, New York, N. Y., a corporation of New York Application April 13, 1955, Serial No. 501,077

18 Claims. (Ci. 23-252) having a supply of a suitable absorbent material, such as -soda-1ime, which is chemically reactive with the carbon dioxide contained in the exhalation gases and is eitective to selectively remove the carbon dioxide therefrom. This type of circuit is well-known for the administration of inhalation anesthetic agents.

Administration by this technique is more economical as compared to other methods of administration in which a part or all of the exhalation gases are discharged to the atmosphere, due to the lower consumption of expensive anesthetic agents and other gases used in the anesthesia. In addition, it has been found that more uniform anesthetic mixtures can be maintained during anesthesia with I the closed technique, and that thermal and moisture losses are greatly reduced, affording significant physiological advantages, highly beneficial to the patient. Such advantages are especially important in the anesthetization of infants and small children; and this method, therefore, is considered, under ordinary circumstances, to be the most preferred technique for administering inhalant anesthetics to such patients.

The proper functioning of the carbon dioxide absorber is essential to the administration of inhalant anesthetics by the closed-circuit technique. Otherwise, the carbon dioxide content of the circuit gases soon increases above a safe level such that adequate ventilation and oxygenation of the patient cannot be maintained. Accordingly, considerable diligence is exercised by the anesthetist in examining the anesthetic apparatus and absorber before the anesthesia and during administration to insure that the equipment is functioning properly at all times. Some types of carbon dioxide absorbent materials widely used in such anesthetic apparatus contain a chemical indicator substance with the soda-lime, which changes color when the absorbent material has become exhausted, thus enabling the anesthetist, readily, to recognize the need for replenishing the supply.

Although provisions are made for the inspection of the absorbent material and for the replacement thereof in the carbon dioxide absorbers presently available, it has bee-n found that such provisions are not entirely satisfactory.

This has been due largely to the cumbersome, impractical construction of such absorbers in which considerable dismantling or disassembly of the absorber may be required to inspect or replace the absorbent material. These manipulations frequently cannot be made without disrupting the operation of the anesthetic circuit, so that a serious problem is created when this must be done during the anesthesia. In addition, most of these devices do not United States Patent permit an accurate determination of the condition of the absorbent, but enable only an approximation to be made. It has also been found that carbon dioxide absorbers heretofore available, conventionally, are arranged and mounted apart from the operating table and, therefore, are not adapted to be conveniently located directly adjacent the patient in the field of the anesthetists immediate attention. Thus, aside from the difiiculties encountered in manipulation of the absorber, it has been heretofore necessary for the anesthetist to direct his attention, periodically, away from the patient to inspect the absorber mechanism and the associated anesthetic circuit. While such difficulties are objectionable for general application, they have hindered the useful application of the closed system technique, particularly, to infants, in whom significant advantages can be obtainedby this method.

It is an object of the present invention to provide an improved carbon dioxide absorber, for anesthetic administering apparatus, which is dependable in operation and in which the inspection and replacement of the absorbent material is greatly facilitated.

It is a further object of the present invention to provide an improved carbon dioxide absorber device, comprising a separate, readily-removable unit adapted to be connected to, and used in conjunction with, standard anesthetic machines and which may be placed advantageously in close vicinity to the patient, upon whom the anesthetists attention is focused.-

it is a further object of the invention to provide an improved carbon dioxide absorber for anesthetic administering apparatus which aifords means for controlling the flow of circuit gases through the absorbent, and in which the replacement of the absorbent material may be accomplished without interrupting the administration of the anesthetic gases to the patient.

Another object of the invention is to provide an improved carbon dioxide absorber, for anesthetic administering apparatus having a self-supporting housing adapted to be placed directly on an operating table surface, in which the absorber canister for holding the absorbent material, is removably disposed at the top thereof in easy reach of the anesthetist.

Another object of the invention is to provide a carbon dioxide absorber for anesthetic apparatus having improved means for mounting the canister, including an adjustable valve member for directing the flow of gases through the absorber and means forming a part of said valve member on which the cannister is received and connected with the anesthetic circuit.

Another object of the invention is to provide in such a carbon dioxide absorber, means for permitting accurate determination of the condition of the absorbent by visual inspection of a true, representative, sample strata thereof.

A still further object of this invention is to provide an improved removable canister for carbon dioxide absorbers in which said canister has inlet and outlet openings adapted to be placed in communication with the breathing circuit, said canister being divided into two compartments for holding absorbent material, each compartment communicating at one end with one of the gas openings and opening at the other end into a common chamber having a removable closure, whereby the circuit gases are conducted successively through the divided compartments from the inlet to the outlet opening, and the adjacent strata of absorbent material in said compartments correspond substantially to the mid-strata of an equivalent single compartment canister, and represent an average sample of the total absorbent supply.

It is a still further object of this invention to provide an improved carbon dioxide absorbent having special 1 3 utility in closed systemaiies'thetic administering circuits, rendering such circuits more efiicacious for the administration of inhalant anesthetics to infants and the like.

- The, invention and other of its advantages maybe betterunderstood by referring to the following description of a preferred embodiment thereof and the accompanying drawings, in which:

Figure l is a view showing a closed anesthetic administering circuit, constituting a circle type rebreathing system, including a carbon dioxide absorber constructed according to the present invention, illustrating the manner in which such apparatus is applied to the patient;

Figure 2 is an enlarged plan View of the closed anesthetic circuit shown in Figure 1;

Figure 3 is a sectional, elevation view of the carbon dioxide absorber, taken along the line 3-3 of Figure 2,

looking in the direction of the arrows;

f Figure 4 is a sectional view taken along the line 4-4 in Figure 3, looking in the direction of the arrows, showing the interior construction of the canister of the carbon dioxide absorber, portions thereof being partly broken away; a

Figure 5 is a sectional .view taken along the line 5-5 in Figure 3, looking in the direction of the arrows;

Figure 6 is a sectional view, taken along line 6-6 in Figure 2, looking in the direction of the arrows, illustrating the construction and arrangement of the inhalation check valve;

Figure 7 is a sectional view, taken along the line 7-7 [in Figure 5, looking in the direction of the arrows, il-

lustrating the construction, and arrangement of the exhalation check valve;

Figure 8 is a bottom plan-"view of the carbon dioxide unit shown in Fig. 3; and

Figure 9 is an exploded isometric view of the carbon dioxide canister and valve mounting means therefor, showing the manner in which these members are assembled.

An anesthetic administering apparatus of the closed circuit type, according to a preferred form of the present invention, is shown in Figure l. The absorber is shown 'in a preferred operative relation to the patient P, for

example a child or an infant, on an operating table 10. The anesthetic breathing circuit includes a face mask 12 placed over the patients nose and mouth, to which are connected an inhalation duct 14 and an exhalation duct 16, in the form of flexible rubber tubes. These breathing ducts are attached, as will be more fully understood hereinafter, to suitable fittings on a carbon dioxide absorber unit designated generally at 18, which includes a breathing bag 20. The apparatus thus connected, forms 'a closed breathing circuit in which the patients exhalaide, or with the vapors of liquid agents such as ethyl ether, trichloroethylene, etc. The machine is regulated such that the volume of the gases consumed by the patient-and extracted in the absorber are replaced by the "delivery gas to maintain the average volume of the system substantially at equilibrium. The depth of anesthesia is controlled by regulating the concentration of the anesthetic gas in the mixture delivered to the breathing circuit, as is well known.

It will be understood that various types of devices for delivering anesthetic mixtures to the breathing circuit may be used and that different well-known types of inhalor devices may be used for connecting the anesthetic catheters having the usual fittings for receiving the inhalation and exhalation tubes of the breathing circuit.

The anesthetic breathing circuit of Figure l is shown in the enlarged plan view of Figure 2. As shown therein, the carbon dioxide absorber 18 comprises a body housing 24 of substantially elongated'shape, which receives the exhalation tube 16 at one end and the inhalation tube 14 at the other end. As shown in Figures 3, 5, and 7, the exhalation tube 16 is attached by means of an inlet fitting 26 through which the exhalation gases are delivered to the absorber. The tubular fitting 26 which is substantially of L-shape, Figure 7, extends through the side wall of the body housing into an inlet chamber 28. The upper end of the tubular fitting terminates in an opening governed by a disc, check-valve element 30, housed within a cage-like guide 32, which permits the check valve element to .move vertically in response to gas flow while maintaining it in proper alignment for seating against the terminal opening of the tubular inlet fitting 26. The check-valve and cagelike guide therefor, are of well-known construction. A transparent plastic dome member 34 is threaded into the absorber body housing forming a closure at the top of the inlet chamber 28 through which the action of the exhalation check-valve element 30 may be observed, making it possible for the anesthetist to determine Whether the patient is breathing properly even .When the patients volume of respiration is extremely small. This arrangement is particularly helpful during anesthetizetion of infants in which the tidal exchangevolume is so small that it is not discernible, frequently, by any visible displacement .of the breathing bag.

-Disposed substantially at the center of the absorber housing is a cannister 35 for holding a supply of absorbent material. The cannister is seated on a supporting valve device, designated generally at 36 through which the cannister may be placed in communication with elongated gas passages 37 and 38 of the absorber as will be more fully described hereinafter. The passa'ge.3'7 extends from inlet chamber 28 to the valve 36 through which exhalation gases are conducted to the cannister and the passage 38 extends toward the opposite end of the absorber housing Where it communicates with a discharge chamber 39 into which the gases from the cannisterare delivered after removal of the carbon dioxide content therefrom. A tubular conduit 40 which is substantially of L-shape, Figure 6, extends from the'discharge chamber 39 into a cavity 41. The upper end of the conduit terminates in an opening having a checkvalve element 42 which is disposed Within a cage-like guide 44. This arrangement is substantially identical to that of the exhalation check-valve 30 and is effective to permit gas to flow from the discharge chamber 39 into cavity 41 but not in the reverse direction. A transparent plastic dome 46, threaded into the absorber housing, forms a closure at the top of the cavity 41 through which the operation of the inhalation check-valve element42 may be observed. Referring to Figure 5, a connector fitting 48 at the side of the absorber housing, opening from the cavity 41, receives the delivery tube 22 through which the anesthetic gas mixture from an anesthetic machine, as previously described, is delivered to the absorber. The inhalation tube 14, through which the mixture of the exhalation gases treated in the absorber and the gas from delivery tube 22 is administered to the patient, is received on a tubular connector 50 communicating with the cavity 41. The respiration gases thus flow within the circuit during inhalation and-exhalation in a single direction as shown by the arrows in Figure 2.

The breathing bag 20 is shown attached to the absorber by a suitable nipple 52 which opens into the elongated passage 38. A second nipple 53.having a removable cap 54 provides a means for alternatively connecting the on the bottom of the valve spindle.

breathing bag in the circuit at the inlet chamber 28. When attached to nipple 52 the bag may be compressed by the anesthetist to assist inhalation while on the nipple 53 it may be used to assist exhalation. The pressure within the breathing circuit is indicated by the reading on a pressure gauge 55, Figure 2, having a threaded nipple 56 which opens into the inlet chamber 28. A pressure relief valve 57, Figure 6, is provided to automatically vent gases from the discharge chamber 39 through a series of outlet openings 58 when the gas pressure in the circuit exceeds a predetermined safe value. The relief valve is of conventional construction having the usual spring biased seating means, not shown, which may be adjusted by control knob 59 to set the operating pressure of the valve.

The supporting valve device 36 for the absorber cannister has a tapered spindle 62 which is received in a tapered valve bore 64, formed in an enlarged boss 66 at the center section of the absorber housing. Inlet and outlet openings are formed in diametrically opposite sides of the valve bore by the terminal ends, respectively, of the gas passages 37 and 38 therein. The valve member is held in place in the valve bore by means of a spring plate 68 which is anchored at its center by a screw 70 A plurality of inturned prongs 72 are forced against the bottom of the absorber housing when the screw 70 is tightened thus producing a downward force on the valve spindle urging it into seating engagement with the tapered valve bore. A suitable lubricant is provided between the engaging valve faces to facilitate rotation of the valve spindle and to assist in creating a gas tight seal. A stop washer 74 carried on the shank of the screw 70 prevents the spring plate from being clamped against the bottom of the spindle by the screw and permits the spindle to rotate without requiring the spring plate to rotate with it.

At diametrically opposite sides of the valve spindle 36, a pair of grooves are provided which form opposite recesses 76 and 77. Passages 78 and 79 within the spindle communicate respectively with the recesses 76 and 77 and open through the top of the valve spindle, forming openingsSfl and 81 therein as may best be seen in Figure 4. A single passage 82 is formed in the valve spindle, Figures 3 and 5, which extends through the spindle along a line substantially transverse to the axis of alignment of the recesses 76 and 77 and substantially in the same horizontal plane therewith. The valve spindle 62 when positioned as shown in Figures 3 and causes the recesses 76 and 77, respectively, to register with the corresponding openings formed by the terminal ends of the elongated gas passages 37 and 38 in the valve bore 64. A continuous gas conducting passage is thereby formed through the passage 37, recess 76, passage 78, cannister 35, passage 79, recess 77, and passage 38. In this position of the valve spindle the ends of the passage 82 are closed by the walls of the valve bore 64. When the valve spindle is rotated 90, these respective connections are reversed such that the ends of the passage 82 are brought into registery with the elongated passages 37 and 38, while, simultaneously, the recesses 76 and 77 are closed off therefrom by the walls of the valve bore. In this position the cannister 35 is isolated from the breathing circuit and the breathing gases are by-passed through the passage 82.

The canister 35 is mounted on and secured to the valve spindle as may best be seen in Figures 3 and 9. Referring thereto, it may be seen that the valve spindle is provided with an annular flange 84 on which the bottom rim of the canister is seated. A layer 86 of any suitable gasket material, such as rubber or the like, is placed on the flange to create a sealing engagement when the canister is in place. The canister which is of cylindrical shape has a vertical partition 88, Figure 4, which extends diametrically across the inside thereof dividing the canister into two separate chambers or compartments 89 and 90. Acover 92 is received on the" top of the canister which is preferably made of a non-breakable, transparent plastic material, or of other suitable transparent material, so that the anesthetist may view the absorbent material in the canister without removing the cover therefrom. An annular rim 34 of rubber or similar gasket material, covers the peripheral edge of the cover to create a gas seal around the upper edge of the canister when the cover is placed thereon. It will be seen by reference to Figure 3 that the vertical partition 88 does not extend to the full height of the canister, and that when the cover and canister shell are assembled, a space is provided at the top thereof, through which gases may flow from one of the canister compartments 89 and 30, to the other.

The absorbent material is placed in the compartments 89 and 90 up to approximately the level of the top of partition 83. The absorbent most commonly used is soda lime mixture, usually containing very small percentages of silica to make the mixture hard and to avoid the formation of soft crumbly masses which might result in alkaline dust. The mixture is formed of coarse granules, usually of 4-8 mesh. Preferably chemical indicators such as ethylviolet or Clayton yellow are added to the soda-lime. These indicators are responsive to the pH of the absorbent and permit the anesthetist to determine the state-of exhaustion of the absorbent by a change in color. These expedients are well known.

Located substantially at the bottom of the cannister is a perforated plate d6 which is adapted to support the absorbent material placed in the cannister compartments. The perforated openings in the plate 36 are of such dimensions that the absorbent particles, of the sizes commonly employed, will not pass through them. Arranged slightly below the perforated plate 96 and carried by a central column 93 is a second plate 100 which projects radially outwardly substantially beyond the top openings 80 and 81 of the valve spindle. This plate has no perforations and acts as a baffle to prevent fine particles and chips produced by handling the absorbent material, which succeed in passing the perforated plate 96, from dropping into the gas passages 78 and 79 at the bottom of the cannister.

The cannister is secured in place by a screw having an enlarged knurled head 102 and an elongated shank 103 which extends downwardly through the canister cover 92 and into the central tubular column 98. At its lower end the screw threads into the valve spindle 62. A gasket washer 104 is positioned between the screw head 102 and the cannister cover to create a gas tight seal when the screw is tightened. A transverse pin 166 is carried in the shank of the screw, the projecting ends thereof providing a stop which prevents the cover 92 from slipping ofi of the screw when the cover assembly is removed from the canister.

As seen in Figure 4, each of the canister compartments 89 and till are arranged to register with one of the open ings 8b and $1 in the top face of the valve spindle. This is accomplished by providing a recess 1% which extends diametrically across the top face of the valve spindle, as seen in Figure 9, between the terminal passage openings 80 and 81. An enlargement 1639 is formed at the center thereof. In order to assemble the canister, the bottom edge of the transverse partition and the central column 98 must register with and be inserted into the recess 108 and enlargement 169. Accordingly, the canister may not be operatively secured in place unless the respective canister chambers are in proper registry with the corresponding passage openings in the valve spindle. As shown in Figure 3, the layer 36 of gasket material extends through the recess 168 and the enlarged circular section 109 thereof, so that the seating-of the partition 88 and of the tubular column 98 thereon produces a sealing contact.

In order that the operator may determine whether the valve spindle is in the position shown in Figures 3 and 5,

ens-7,413

ecori'espondin'g to its oniposition in which the canister is .cdnnected in the breathing circuit, or whether the spindle is positioned in its ofi position in which the canister is cut offifrom the breathing circuit, a stop device is pro vided in the form of the boss 110, seen in Figure 8. The

boss 110 projects downwardly from the underside of the flange 34 of the valve spindle and permits the spindle to -.be rotated between the position corresponding to that shown by the location of the boss shown in Figure 8 and the opposite position corresponding to that indicated by the boss 110 shown in phantom lines in Figure 8. In the first position, the valve spindle connects the canister in the breathing circuit as shown in Figure 3. In the op- -posite position, the spindle is rotated 90 from the first position and causes the canister to be closed from the breathing position. At intermediate positions controlled portions of the total flow may be directed through the can 'ister. Suitable directional arrows and the words on and off corresponding to the direction of rotation of the spindle are provided on the rim of the canister cover as seen in Figure 2. It will be noted that the rim is provided with knobs for gripping purposes and that when the anesthetist grasps the cover and rotates the canister in the desired direction, the spindle is caused to turn therewith since the canister and valve spindle means comprise a unitarily assembled structure. When the canister is in --oft position, it may be removed for replenishing the supply of absorbent material without interfering with the patients respiration.

The shape of the absorber body housing and the general arrangement of the -elements thereof afiord special ad vantages in permitting the placement of the absorber directly on the operating table during use, and in facilitating the inspection and replacement of the carbon dioxide absorbent material. It will be noted, as best seen in Figure 3, that the outer ends of the absorber housing are stepped downwardly and lie substantially in a single plane Which is beyond the protruding portions of the valve spindle at the bottom of the absorber housing. Consequently, the absorber housing is self-supporting and is adapted to be placed on a flat surface with the canister disposed in a substantially upright position at the top of the body housing, without additional supporting fixtures and the like. The pressure gage 55 is attached to the absorber housing in such a way that its rear face coincides substantially with the plane, of the bottom supporting sur faces of the absorber housing, thereby furnishing an additional extension thereof which lends greater stability to the absorber when it is placed on a fiat supporting surface.

This construction is of particular usefulness when the .absorber is used during the administration of anesthetic to infants. Due to their small size, infants occupy only a small space on the operating table and in order to reach the patient the anesthetist may be required to bend over the table or to move from his customary place at the head end of the table. With standard type anesthetic administering apparatus which wili thus be further removed from the immediate field of interest, this may further add to the inconvenience of the operating and supervising the anesthetic apparatus during the anesthesia. As a results of the desirable arrangement described above, however, the entire absorber unit may be placed on the operating table, as shown in Figure 1 in the convenient reach of the anesthetist where he'will have little difiiculty in attending to its proper functioning. The absorbent material is directly visible at all times to the anesthetist through the transparent canister cover and may be easily replaced, if the occasion demands without disturbing the absorber housing.

' In the event that it is not desired to take advantage of these features of construction, the absorber need not be placed directly on the operating table but may be supported in other ways, near the operating table, similar to. the more conventional methods presently in use.

above may be used for the administration of an inhalant anesthetic to a patient as follows:

The closed circuit formed as shown in Figure 2 is usually first tested to determine that the emergency relief valve 59 is properly set. This is readily accomplished by the anesthetist breathing into the inhaler mask while observing the pressure reading of the gage 55 and simultaneously adjusting the knob of the relief valve until the desired maximum pressure is maintained as shown by the pressure indicator. The pressure read on the indicator is the pres sure at which the relief valve will open to prevent further pressure increase, should such an excessive pressure gccur during the operation of the anesthetic apparatus.

The delivery tube 22 is attached to the absorber and the mask applied to the patient as shown in Figure 1, after rotating the cannister in the on direction as indicated by the arrows on the cover of the cannister, and placing the cannister in its on position, the anesthetist is ready to commence administration.

During the initial administration, relatively high concentrations of anesthetic gas are normally used to induce anesthesia in a relatively short time. As the desired level of anesthesia is reached, the anesthetic concentrations are adjusted, to provide concentrations adequate to maintain such desired level or to produce other effects, as is well known to those skilled in anesthetic administration. As the patient breathes, the exhalation gases are permitted to pass through the exhalation check-valve 3b of the absorber into passage 37, recess 76, passage 78 and thence into the canister. The exhalation gases are then passed upwardly through one side of the canister in direct contact with the carbon dioxide absorbent material in the first compartment, over the top of the separating partition 38 and thence downwardly through the second compartment in direct contact with the second batch of absorbent material. It does not make any diiference in the operation of the absorber which of the compartments-89 or is disposed over the top of the inlet passage 78 since it will be seen that in any event the gas passes successively through each of the chambers en route, from inlet passage 78, to the opposite passage 79. From the passage 79 the gases are conducted to the valve recess '77, passage 38 to the discharge chamber 39. Upon each inhalation check-valve 42 is opened allowing the conditioned gases to fiow from the discharge chamber to cavity 41 and thence into inhalation tube 14 to the patient.

In the extreme position in the on direction all of the respiration gases are passed through the canister which efiectively maintains the carbon dioxide content of the respiration gases at a minimum as long as the absorbent material is active. Under certain conditions it may be desired to raise the carbon dioxide content of the gases slightly to bring about certain desirable conditions in the patient, as is well known to those skilled in the art of anesthetic administration. For example, a higher level of carbon dioxide content may be maintained for certain intervals in order to increase the patients voluntary rate of respiration. When such conditions are required, the anesthetist may rotate the canister to intermediate positions between the extreme on and ed positions, in which varying amounts of the respiration gases will bypass the canister through the connecting passage 82 of the valve spindle. It will be seen that in such intermediate positions, the passages connecting the canister in the breathing circuit and the by-pass conduit 82 areboth 9 placed in communication with the breathing circuit. The further the canister is rotated toward the off position, the greater will be the percentage of the gases diverted through by-pass conduit 82, and the greater will be the level of carbon dioxide content in the circuit.

During the anesthesia the anesthetist may periodically observe the condition of the absorbent material by looking through the transparent cover of the canister. When the absorbent contains a chemical indicator substance, a change in the color of the absorbent supply will signal the need for replacement. Similarly, the anesthetist continually watches the patient for signs, well known to him, which occur when the carbon dioxide content of the gases increases above the normal level, likewise indicating a need for replenishing the absorbent. In the event that such a need arises, the anesthetist rotates the canister to the off position. At this position the canister is isolated from the breathing circuit while, at the same time, the breathing circuit is completed through the by-pass passage 82 of the absorber valve, allowing the patient to continue breathing in the circuit without interruption. The anesthetist then unthreads the retaining screw 102 which makes it possible to remove the canister from the absorber housing. Normally, the anesthetist has on hand a second canister charged with a fresh supply of absorbent which he then substitutes in place of the canister which has been removed. The retaining screw 102 is then reinserted through the central tubular column 98 and v threaded into the valve spindle 62 to secure the replacement canister in place. When this has been done the canister is again rotated to on position, so that the respiration gases are once more passed through the absorbent material. It will be seen that the entire operation of replacing the canister takes but a very short time during which a substantially negligible amount of carbon dioxide is accumulated in the closed breathing circuit, which will not harmfully affect the patient. Once the 1 fresh supply of absorbent is placed in operation, the carbon dioxide concentration is rapidly reduced to a suitable level.

The canister compartments S9 and 9%, it will be seen, constitute two substantially identical chambers connected in series in the breathing circuit when the canister is in its on position. Accordingly, the top layer of absorbent material in each of the chambers lie substantially at the mid-point of the effective, total bed of absorbent material through which the gases pass, and reflect substantially the average condition of the total absorbent supply. In a single, continuous type chamber, the mid-strata is not directly visible, and even when provision is made for permitting inspection of the absorbent, the anesthetist can only approximate the condition of the absorbent supply by evaluation of the visible strata thereof. However, as a result of the advantageous construction and arrangement of the canister 35, according to the present invention, the anesthetist is permitted to observe, directly, the material at the effective mid-strata of the absorbent supply and thus obtain a true evaluation of the condition of the supply.

This invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit, as defined by the following claims.

I claim:

1. A carbon dioxide absorber for anesthetic administering apparatus having a canister through which anesthetic gases are adapted to be passed comprising, a housing having inlet and an outlet gas passages, a valve member adjustable to oil and on positions received in said housing, having a passage forming a connecting duct between said inlet and said outlet passages in the off position of the valve element, second and third passages, in said valve element adapted to register respectively with said inlet and outlet passages in the on position of said valve element, said second and third passages, terminating in corresponding openings in a canister receiving portion of said valve element externally of said housing, and a canister removably mounted on said canister receiving portion of said valve element in communication with said openings, such that gases are passed through said canister when the valve element is in on position.

2. A carbon dioxide absorber as set forth in claim 1 wherein the valve element is provided with means cooperating with said housing to indicate when said valve has been adjusted to said on and off positions, respectively.

3. A carbon dioxide absorber as set forth in claim 1 wherein said valve element comprises a valve spindle received in a corresponding valve bore in said housing, a portion thereof projecting externally of the housing on which said canister is received, and said first passage, and said second and third passages are formed in said valve spindle and arranged to register with said inlet and outlet passages, respectively, in corresponding angular positions of said valve spindle.

4. A carbon dioxide absorber as set forth in claim 3 wherein said external portion of said valve spindle comprises an annular flange having a flat seating surface and said canister comprises a cylindrical container, one end of which is open and is seated in a gas tight manner on said flange.

5. A carbon dioxide absorber as set forth in claim 4 wherein said canister is divided into two separate compartments, each disposed opposite and in communication respectively with one of said openings of said valve element at one end and having passage means at their opposite ends interconnecting said chambers.

6. A carbon dioxide absorber as set forth in claim 5, having positioning means effective to orient said canister with respect to said valve spindle, when assembled, such that each of said compartments of said canister register with only one of said openings formed in the external portion of said spindle.

7. A carbon dioxide absorber as set forth in claim 6 wherein said positioning means comprises a recess formed in said valve spindle and a projecting portion of said canister which is received therein when said canister and said spindle are properly oriented.

8. A carbon dioxide absorber as set forth in claim 7 wherein said recess extends across the, external portion of said valve spindle between said openings therein, and said projecting portion comprises a partition member effectively dividing sad canister into the two said compartments.

9. A carbon dioxide absorber adapted to be connected to a respiratory circuit for eifecting the removal of carbon dioxide from respiratory gases, comprising a selfsnpporting housing having a gas inlet and a gas outlet through which respiratory gases are delivered to and from said housing, a canister detachably mounted at the topside of said housing having a charge chamber, through which the respiratory gases are passed, containing a charge of absorbent material, and mounting means for receiving said canister forming a gas connection between said canister and said gas inlet and outlet, said mounting means having a substantially horizontal surface on which said canister is received and conduits communicating respectively with said inlet and outlet which open into said canister receiving surface to form corresponding inlet and outlet apertures, and said canister having corresponding inlet and outlet openings in the bottom thereof in registry with said apertures, said openings connecting with opposite ends of said charge chamber to permit the circulation of gases therethrough, and means forming a removable closure for said charge chamber at the top of said canister.

10. A carbon dioxide absorber as set forth in claim 9 wherein said canister is a generally cylindrical container having means extending across said inlet and outlet openings for retaining a supply of the absorbent material .placed in'said charge chamber, and having means for effectively conducting gases from said inlet, through said absorbent material, to said outlet opening.

11. A carbon dioxide absorber as set forth in claim 10 wherein said charge chamber is divided into first and second longitudinal compartments connecting at their lower ends respectively, with said inlet and outlet openings and confronting a common manifold chamber at the upper end of the canister.

12. A carbon dioxide absorber as set forth in claim 11 wherein said removable cover is transparent.

13. A carbon dioxide absorber comprising a housing having passage means adapted to be connected in a breathingcircuit, a canister removably mounted on said housing having an inlet and outlet in communication with said passage means when said canister is operatively mounted on said housing such that respiration gases are conducted through said canister, said canister comprising a container having first and second vertically extending compartments each adapted to receive a substantially identical supply of carbon dioxide absorbent material therein, means connecting said inlet an doutlet openings respectively with the lower ends of said compartments, means forming a space at the top of said container into which the upper ends of said compartments open such that the respiration gases pass upwardly through one of said compartments and downwardly through the other, and a removable transparent cover forming a closure for the top of said container through which the upper strata of absorbent material in said compartments are visible.

14. A carbon dioxide absorber comprising a housing having inlet and outlet passages adapted to be connected to a breathing circuit, a substantially cylindrical canister for holding a supply of carbon dioxide absorbent material and means for removably mounting said canister on the top portion of said housing in a generally upright position, said mounting means having ports corresponding respectively with said inlet and outlet passages and being arranged to receive the lower open end of said canister such that said ports register therewith, partition means forming two separate longitudinal compartments in said canister each of which communicates with one of said ports at its lower end, a perforated member disposed at the lower end of each of said compartments for supporting a bed of absorbent thereon, a chamber in the upper portion of said canister into which the upper ends of said longitudinal compartments open, and a removable transparent cover seated on the upper end of said canister through which the surface strata of the respective beds of absorbent are visible.

15. A carbon dioxide absorber as set forth in claim 14 wherein said ports are disposed in confronting relation, respectively, with the lower ends of said compartments and a baffle element is interposed between each of said ports and the lower ends of the respective compartments, below said perforated members, eifective to prevent particles of absorbent material which may pass through said perforated members from dropping into said ports.

16. A carbon dioxide absorber as set forth in claim 14 wherein a centrally disposed tube extends longitudinally through said canister, a stem having an enlarged outer end extends through said cover and said tube, and means are provided for threadedly receiving the inner end '12 of said stem in said mounting means for effectively securing said cover and canister on said absorber in a gastight manner.

17. A carbon dioxide absorber adapted to be connected to an anesthetic circuit for removing carbon dioxide from recycle respiratory gases comprising a housing having a gas inlet and a gas outlet for delivering circuit gases to and from said absorber housing, valve means adjustably received in said housing including valve passages arranged selectively to be connected with said inlet and outlet, and a canister for holding a supply of absorbent material, detachably mounted on an external portion of said valve means, said valve passages including delivery passages adapted to communicate with said'canister to effect the circulation of said respiratory circuit gases therethrough and separate by-pass passage means adapted alternatively to directly interconnect said inlet and outlet such that in one position of said valve respiratoryv gases are circulated through said canister and in a second position and said valve said by-pass passage means directly interconnects said inlet and outlet and said delivery -pas sages are occluded thereby isolating said canister from the gases conducted through said absorber housing.

18. A carbon dioxide absorber, having a charge of carbon dioxide absorbent material, adapted to be connected in a respiratory circuit to elfect the removal of carbon dioxide from respiratory gases by contact of said gases with said absorbent, comprising a housing having respiratory-gas, circulating passages, a canister for holding a supply of absorbent material removably mounted on said housing and having openings forming an inlet and an outlct, respectively, connected with said respiratory-gas circulating passages through which such gases are conducted to and from said canister, means forming a partition separating said canister inlet and outlet and forming separate, corresponding compartments which communicate at one end, respectively, with said inlet and outlet openings, said compartments being adapted to receive separate, substantially equivalent changes of absorbent, a manifold chamber into which the opposite ends of each of said compartments open such that gases circulated through said canister pass successively from said inlet through one of said compartments, said manifold chamber, and through said other compartment to said outlet, and means forming a transparent wall portion of said manifold chamber disposed in confronting relation to the exposed ends of said compartments, through which the exposed strata of absorbent material in said compartments corresponding substantially to the effective mid strata of the total absorbent charge may be visually observed.

References Cited in the file of this patent UNITED STATES PATENTS 1,541,147 lkeda et al. June 9, 1925 2,121,196 Heindbrink June 21, 1938 2,222,882 Shames Nov. 26, 1940 2,248,956 Carvlin July 15, 1941 2,314,119 Borchardt Mar. 16, 1943 2,450,338 Heindbrink Sept. 28, 1948 2,678,108 Reid May 11, 1954 FOREIGN PATENTS 393,094 Great Britain June 1, 1933 UNITED sures PATENT erri'ci: CERTlFlCATE @l '66 EQTION Patent No.: 2,837,413

June 3 1958 Wayne W Elay It is hereby certified that error appears in the-printed specification of the above "numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column '7, line 61, for "results" read me result column 10, line '74, after "having" insert m perforated supporting column 11,

9 line 22., for "an doutlet" read. and outlet column 12, line 20, for "and" read of line 39, for "changes" read charges Signed and sealed this llth day of November 1958 (SEAL) Attest:

KARL OBERT C. WATSON Attesiing Ofiicer Commissioner of Patents 

1. A CARBON DIOXIDE ABSORBER FOR ANESTHETIC ADMINISTERING APPARATUS HAVING A CANISTER THROUGH WHICH ANESTHETIC GASES ARE ADAPTED TO BE PASSED COMPRISING, A HOUSING HAVING INLET AND AN OUTLET GAS PASSAGES, A VALVE MEMBER ADJUSTABLE TO "OFF" AND "ON" POSITIONS RECEIVED IN SAID HOUSING, HAVING A PASSAGE FORMING A CONNECTING DUCT BETWEEN SAID INLET AND SAID OUTLET PASSAGES IN THE "OFF" POSITION OF THE VALVE ELEMENT, SECOND AND THIRD PASSAGES, IN SAID VALVE ELEMENT ADAPTED TO REGISTER RESPECTIVELY WITH SAID INLET AND OUTLET PASSAGES IN THE "ON" POSITION OF SAID VALVE ELEMENT, SAID SECOND AND THIRD PASSAGES, TERMINATING IN CORRESPONDING OPENINGS IN A CANISTER RECEIVING PORTION OF SAID VALVE ELEMENT EXTERNALLY OF SAID HOUSING, AND A CANISTER REMOVABLY MOUNTED ON SAID CANISTER RECEIVING PORTION OF SAID VALVE ELEMENT IN COMMUNICATION WITH SAID OPENINGS, SUCH THAT GASES ARE PASSED THROUGH SAID CANISTER WHEN THE VALVE ELEMENT IS IN "ON" POSITION 